Oxygen enriched combustion and co-combustion of lignites and biomass in a 30Â kWth circulating fluidized bed

•Two different lignites, one biomass and their blends were combusted in different oxygen enriched atmospheres.•Effect of oxygen enrichment on flue gas composition was investigated.•Oxygen enrichment increases fuel-N conversion and SO2 formation.•CO2 concentration in flue gas reached up to 23% in 30% oxygen enriched co-combustion.

Oxygen enriched combustion is a promising retrofitting option for existing power plants to improve CO2 capture. In this study, the effect of oxygen enrichment of air as oxidant was investigated with a 30kWth fluidized bed combustor. Tests were conducted with two different Turkish lignites, one biomass and their blends. Biomass share was increased up to 20%. The oxygen concentration in the oxidant was kept between 21 and 30%.Oxygen enrichment supports combustion in all cases. Biomass addition to lignites appears to have an increasing synergetic effect on combustion as the oxygen enrichment and biomass portion in the mix increases. It was found that oxygen enrichment increases NO and SO2 formation in all cases. As the biomass share increases NO emissions increase in all oxygen cases while the opposite is true for SO2 emissions.